Editorials
In the face of uncertain funding, the US initiative should not ignore proven programmes in favour of glitzy research.
doi: 10.1038/539467a
But grave challenges remain before the promise of individually tailored medicine becomes reality.
doi: 10.1038/539467b
The SESAME synchrotron shows a way towards greater trust and cooperation in the Middle East.
doi: 10.1038/539468a
News
SESAME project is set to revolutionize science in the region but is strapped for cash.
doi: 10.1038/539475a
Worries include job prospects, discrimination — and safety.
doi: 10.1038/539476a
Drilling into Mexico’s Chicxulub basin also finds shattered rock where underground life could thrive.
doi: 10.1038/nature.2016.20994
The move by Chinese scientists could spark a biomedical duel between China and the United States.
doi: 10.1038/nature.2016.20988
Cap at current spending levels could spell ‘end of science in Brazil’, researchers say.
doi: 10.1038/nature.2016.21014
Project to sequence the DNA of more than 1,000 species seeks to reveal how bats learn to communicate.
doi: 10.1038/nature.2016.20997
News Features
Elaina Tuttle spent her life trying to understand the bizarre chromosome evolution of a common bird — until tragedy struck.
doi: 10.1038/539482a
News & Views
Repair enzymes must communicate across hundreds of nucleotides to undo errors made during DNA replication. Imaging reveals that the enzymes do this by forming a series of ring-like clamps that diffuse along the DNA. See Letter p.583
doi: 10.1038/nature20475
Organic semiconductor devices require good electrical contacts with conducting materials, but such contacts are often inefficient. An approach that tackles this problem will enable a wide range of applications. See Letter p.536
doi: 10.1038/539499a
Observations of a real-time invasion of Australia by Asian honeybees demonstrate how natural selection can allow a small founding population to overcome the genetic odds stacked against success.
doi: 10.1038/nature20472
Previous observations showed that friction on graphene increases gradually when a probe starts to slide across the material's surface. Simulations now reveal that this effect is related to bending of the graphene sheet. See Letter p.541
doi: 10.1038/539502a
Injured blood vessels are repaired by vascular smooth-muscle cells. It emerges that the protein Fat1 regulates the proliferation of these cells by inhibiting the function of mitochondria. See Letter p.575
doi: 10.1038/nature20476
A biocompatible probe that combines fluorescent nanodiamonds and gold nanoparticles allows cells to be imaged using both optical and electron microscopy techniques, opening up fresh opportunities for biological research.
doi: 10.1038/nature20478
Plants and bacteria battle for control of water during leaf infection, as is demonstrated by a bacterial species that manipulates plant cells to create a water-rich environment that promotes bacterial growth. See Article p. 524
doi: 10.1038/539506a
Review
The interplay between spin–orbit coupling and two-dimensionality has led to the emergence of new phases of matter, such as spin-polarized surface states in topological insulators, interfacial chiral spin interactions, and magnetic skyrmions in thin films, with great potential for spin-based devices.
doi: 10.1038/nature19820
Articles
Alx3-induced modulation of Mitf expression alters melanocyte differentiation and gives rise to the hair colour differences underlying the repeated evolution of dorsal stripes in rodents.
doi: 10.1038/nature20109
A combination of high humidity and bacterial effectors, such as Pseudomonas syringae HopM1, creates an aqueous environment in the apoplast of immunodeficient Arabidopsis thaliana that allows non-pathogenic P. syringae strains to become virulent pathogens.
doi: 10.1038/nature20166
The mystery of how bacteria that lack motile structures such as pili or flagella can ‘glide’ along surfaces is solved by a detailed description of the bacterial focal adhesion complex and its associated protein machinery.
doi: 10.1038/nature20121
Letters
A general strategy for producing solution-processed doped polymers with the extreme work functions that are required to make good ohmic contacts to semiconductors is demonstrated in high-performance light-emitting diodes, transistors and solar cells.
doi: 10.1038/nature20133
Atomistic simulations reproduce experimental observations of transient frictional strengthening of graphene on an amorphous silicon substrate, an effect which diminishes as the number of graphene layers increases.
doi: 10.1038/nature20135
In the chemical industry, it is often necessary to activate carbon–carbon bonds in order to synthesize complex organic molecules, but this is challenging when starting with simple five- or six-membered carbon rings; a new method uses a rhodium pre-catalyst and an amino-pyridine co-catalyst, enabling an overall energetically favourable reaction that involves activation of carbon–carbon bonds plus activation of carbon–hydrogen bonds.
doi: 10.1038/nature19849
Polarity reversals caused by dynamo waves are demonstrated in a magnetohydrodynamic model that is relevant to planetary cores, suggesting a possible mechanism of geomagnetic reversals.
doi: 10.1038/nature19842
Cannabinoids affect CB1 receptors on the mitochondrial membranes in the brain, triggering a decrease in downstream cAMP-dependent signalling; this leads to a decrease in brain mitochondrial activity and to cannabinoid-induced amnesia.
doi: 10.1038/nature20127
The authors have designed modular synthetic hydrogel networks for mouse and human intestinal stem cell cultures that support intestinal organoid formation.
doi: 10.1038/nature20168
Apoptotic intestinal epithelial cells can be sampled by lamina propria phagocytes, leading to distinct phagocyte-type-specific anti-inflammatory gene signatures and dendritic-cell-mediated induction of regulatory T cells.
doi: 10.1038/nature20138
Macrophage-derived insulin-like growth factor enhances the uptake of microvesicles by non-professional phagocytes, such as airway epithelial cells and fibroblasts, thereby dampening tissue inflammation.
doi: 10.1038/nature20141
Fragments of the atypical cadherin Fat1 accumulate in the mitochondria of vascular smooth muscle cells where they reduce respiration, leading to a regulated proliferative response to arterial injury.
doi: 10.1038/nature20170
SCAF1 is always required for the interaction between the respiratory chain complexes III and IV, and in animals carrying only the short isoform of SCAF1, the respirasome is absent in most tissues, with the exception of heart and skeletal muscle, where COX7A2 is present instead of SCAF1.
doi: 10.1038/nature20157
MutS and MutL—the highly conserved core proteins responsible for the repair of mismatched DNA—form sequential stable sliding clamps that together modulate one-dimensional diffusion along the DNA and, with MutH, facilitate the search for a distant excision initiation site.
doi: 10.1038/nature20562
Small regulatory RNAs guide Argonaute (Ago) proteins in a sequence-specific manner to their targets and therefore have important roles in eukaryotic gene silencing. Of the three small RNA classes, microRNAs and short interfering RNAs are processed from double-stranded precursors into defined 21- to 23-mers by Dicer, an endoribonuclease with intrinsic ruler function. PIWI-interacting RNAs (piRNAs)—the 22–30-nt-long guides for PIWI-clade Ago proteins that silence transposons in animal gonads—are generated independently of Dicer from single-stranded precursors. piRNA 5′ ends are defined either by Zucchini, the Drosophila homologue of mitoPLD—a mitochondria-anchored endonuclease, or by piRNA-guided target cleavage. Formation of piRNA 3′ ends is poorly understood. Here we report that two genetically and mechanistically distinct pathways generate piRNA 3′ ends in Drosophila. The initiating nucleases are either Zucchini or the PIWI-clade proteins Aubergine (Aub) or Ago3. While Zucchini-mediated cleavages directly define mature piRNA 3′ ends, Aub/Ago3-mediated cleavages liberate pre-piRNAs that require extensive resection by the 3′-to-5′ exoribonuclease Nibbler (Drosophila homologue of Mut-7). The relative activity of these two pathways dictates the extent to which piRNAs are directed to cytoplasmic or nuclear PIWI-clade proteins and thereby sets the balance between post-transcriptional and transcriptional silencing. Notably, loss of both Zucchini and Nibbler reveals a minimal, Argonaute-driven small RNA biogenesis pathway in which piRNA 5′ and 3′ ends are directly produced by closely spaced Aub/Ago3-mediated cleavage events. Our data reveal a coherent model for piRNA biogenesis, and should aid the mechanistic dissection of the processes that govern piRNA 3′-end formation.
doi: 10.1038/nature20162
Characterization of the first Per-ARNT-Sim enzyme, a haem-dependent oxidative N-demethylase.
doi: 10.1038/nature20159